Hire the intern as CEO. Seriously—Just Do It.

But when he walked into the company’s Midwest regional sales office for his first day of work, there was just one problem. Hill’s new boss told him that it wasn’t exactly a job. It was actually going to be a six-month internship.

“An internship?" he thought.

It was an inauspicious start, but Hill lasted longer than six months at Nike. In fact, he would spend his entire career at the same company. He started in 1988 and got promoted every few years for the next few decades. By the time he retired in 2020, he was president of Nike’s consumer division.

But he was recently lured back for one last job—and this time, it wasn’t an internship.

He was just hired as the next CEO.

When John Donahoe abruptly stepped down as Nike’s chief executive last week, his ouster marked the end of a rough stretch in which the company lost its edge—and billions of dollars in market value. Before he was named CEO, he’d never worked at Nike. He’s being replaced by someone who’s basically his exact opposite.

Hill, a 60-year-old company lifer who calls Nike “a core part of who I am," is the latest example of a curious business archetype: the Intern CEO.

Doug McMillon started at Walmart as an hourly associate unloading trailers. Mary Barra worked for General Motors as a student before she took a full-time job on the assembly line inspecting fenders and hood panels. Christian Klein hauled monitors from the basement of SAP’s headquarters to the engineers and developers upstairs. “And not flat screens," he told me. “The heavy ones."

All three have been with their companies ever since. All three are now leading those companies.

When Ursula Burns was a summer intern at Xerox in 1980, it was completely unimaginable to her that she would one day be CEO.

“I didn’t know that we had a CEO," she told me.

But after getting her master’s degree in mechanical engineering, Burns started moving up the Xerox corporate ladder. She worked in the research lab, business planning, the C-suite, global manufacturing and internal operations. Then she ran the whole company from 2009 to 2016.

Starting at the bottom of a company and climbing to the very top has always been an improbable career path. But these days, it feels closer to impossible.

The median job tenure of U.S. workers has dropped below four years, the lowest number in decades, according to newly published federal data, as job-hopping has become increasingly common for talented young employees. Mobility is hot. Loyalty is not. Which means Intern CEOs might be a dying breed.

They may not have firsthand knowledge of how other companies function, but they do have institutional knowledge of their own. They remember which ideas worked and why. They also remember every cockamamie strategy suggested by people who knew precisely nothing about the company but pretended to know it all. What they lack in perspective, they make up for with experience. Where outsiders see problems, interns see promise. And they have the credibility to sell their vision for change when it’s necessary.

“If you’re going through a transition in the company," Burns said, “having someone who understands the heart and soul of the place is valuable."

Nike is currently going through one of those transitions.

As my colleague Inti Pacheco has explained, the company made a series of costly strategic missteps in recent years, like sprinting away from retail stores and toward e-commerce. Meanwhile, increased competition and stalled innovation resulted in meager sales, sunken morale and something of an identity crisis for the sneaker giant.

This company founded by runners even missed out on America’s latest running boom. The only thing more blasphemous for Nike would be losing Michael Jordan to Hoka.

Nike fell behind under Donahoe, whose experience at the company before he took over was limited to a board seat. He spent the formative part of his career at Bain, where he started as a lowly associate consultant and became CEO. He left for the top jobs at eBay and ServiceNow. Nearly five years ago, he traded software for shoes and found himself running Nike.

In other words, he was the epitome of a Consultant CEO. He’s being replaced by the quintessential Intern CEO.

Hill’s first job out of college was an entry-level position on the training staff of the Dallas Cowboys, where he worked for a year before pursuing his master’s degree in sports administration. While he was at Ohio University for graduate school, he took a class on sports marketing and wrote a paper about one of his favorite brands: Nike.

So when a Nike executive named Tim Joyce visited campus, Hill arranged for a meeting, put on his best suit and begged for a job. Then he kept pestering Joyce for months. As graduation approached, Hill promised to never call him again if there was no way he would get hired. Otherwise, he was going to keep calling until Joyce said no. He finally said yes on a Friday. Hill started on Monday.

“I never told my mom it was an internship," he said on the Fortitude FW Podcast last year. “I told her I got hired."

Once he managed to get his foot in the door, he never let it close on his Nikes. As an intern, he packed boxes in the warehouse and picked up phones whenever the office needed help with customer service. “I pretty much did everything they asked me to do—and then some," he says.

At the time, he was still paying off his student loans. But with that attitude, he turned his internship into a proper job as an apparel sales representative. Over the next two years, he put 120,000 miles on his Chrysler minivan.

There was nothing even remotely glamorous about this work: The man was going to mom-and-pop shops in Texas and Oklahoma peddling Lycra.

Hill was so far down the org chart and so far away from corporate headquarters that it took a decade for Nike co-founder Phil Knight to have any clue who he was.

Even today, when the subject turns to the company’s chairman emeritus and largest individual shareholder, Hill sounds like an intern ready to fetch coffee. In reverential tones, he calls Knight the most inspirational person he’s ever met—and “the person I tried the hardest to make proud." And he did: Knight himself led the push tobring Hill back.

Now the company is in the hands of somebody who cares about Nike and its culture so deeply that he cries when he talks about how much the brand means to him—somebody willing to do everything he’s asked and then some.

It worked for Hill as an intern. It might just work for him as the Intern CEO.

Write to Ben Cohen at ben.cohen@wsj.com